Adjustable grinding tool for brake cylinders and the like

ABSTRACT

A grinding tool has a hollow hub at one end to which is pivotally mounted three arms each of which carries a pivotable shoe having mounted thereon a grinding stone. The arms may be radially contracted and held by an axially movable sleeve on the hub which has a radial annular flange serving as an abutment to limit axial advance of the tool in a cylinder being ground. A spring catch member on each of the shoes engages a camming edge of a hole in the arm to disengage the shoes. An adjustment means for setting the maximum radial expansion of the arm includes a spring loaded plug in the hub bearing on notches in the ends of the arm.

United States Patent 1191 Besenbruch et al.

1 1 Jan. 30, 1973 1 ADJUSTABLE GRINDING TOOL FOR BRAKE CYLINDERS AND THE LIKE [75] Inventors: Alex Besenbruch, Greenlawn, and;

Arthur R. Hofmann, Huntington,

both of-N.Y.

[73] Kssignee: Besenbruch Hoi'man, Inc., Lindenhurst,N.Y.

22 Filed: Oct. 28, 1971 [21] Appl. No.: 193,359

52 vs. c1 ..s1/3s3 s1 1m. 01. .3241, 5/08 58 Field t Search .51/331, 332 341, 352, 353

[56] References Cited UNITED STATES PATENTS 3,334,453 8/1967 Von Tersch ..51/353 3,065,579 11/1962 Clark 2,736,146 2/1956 Brooks .Q ..51/341 Primary Examiner-Donald G. Kelly Att0rneyEdward H. Loveman [57] ABSTRACT A grinding tool has a hollow hub at one end to which is pivotally mounted three arms each of which carries a pivotable shoe having mounted thereon a grinding stone. The arms may be radially contracted and held by an axially movable sleeve on the hub which has a radial annular flange serving as an'abutment to limit axial advance of the tool in a cylinder being ground. A spring catch member on each of the shoes engages a camming edge of a hole in the arm to disengage the shoes. An adjustment means for setting the maximum radial expansion of the arm includes a spring loaded plug in the hub bearing on notches in the ends of the arm.

l0-Claims, 6 Drawing Figures PATENTEDJAN 30 ms 3.713256 SHEET 1 BF 2 ALEX BESENBRUCH Y 8\ ARTHUR RHOFMANN BY A TI'ORNE Y PATENTEDJAN 30 [an SHEET 2 OF 2 ALEX BESENBRUCH SKYARTHUR RHOFMANN A TI'ORNEY ADJUSTABLE GRINDING TOOL FOR BRAKE CYLINDERS AND THE LIKE This invention concerns an improved grinding tool and more particularly concerns an improved grinding tool for grinding the internal surfaces of a brake cylinder and similar cylinders.

l-leretofore grinding tools used for the interiors of brake cylinders have had fixed dimensions and there were no means for automatically adjusting the tool to the diameter of cylinder being ground. Moreover the prior grinding tools employed large, expensive, grinding stones which were fixed in place and which were extremely difficult to replace when worn.

The present invention makes a new approach to the problems and difficulties encountered in grinding brake cylinders. According to the invention there is provided a tool having a motor driven hub with a plurality of spring loaded arms pivotally mounted thereto and carrying small removable grinding stones. The arms may be retracted radially and inserted into the cylinder to be ground. When released the arms expand until the grinding stones contact the interior of the cylinder. The arms can be rotated as a unit circumferentially inside the cylinder while the tool is advanced axially inside the cylinder and the grinding stones grind the inside wall of the cylinder. A means is provided to stop or limit axial movement of the tool through the cylinder and beyond the inside wall being ground. Additional means are provided to set a maximum radial spacing of the grinding stones, depending on the diameter of the cylinder to be ground.

It is therefore the principal object of the present invention to provide a grinding tool having a motor driven hub carrying a plurality of pivotally mounted spring loaded arms, each having a removable pivoting shoe carrying a grinding stone.

A further object of the present invention is to provide a grinding tool as described with means for adjusting the spring loading on the arms to adjust the radial spacing of the grinding stones.

Another object of the present invention is to provide a grinding tool as described with quick engagement and disengagement means for the shoes carrying the grinding stones.

Still another object of the present invention is to provide a grinding tool as described with a movable sleeve for holding the arms in radially retracted position while being inserted through a hole in the end wall of a hollow cylinder to be ground.

Yet another object of the present invention is to provide a grinding tool as described with an annular abutment on the movable sleeve to limit axial movement of the tool in the cylinder being ground.

These and other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which:

FIG. 1 is a side elevations view of the grinding tool embodying the invention;

FIG. 2 is a longitudinal, central sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a botton plan view taken along line 3-3 of FIG. 1;

FIG. 4 is an enlarged longitudinal sectional view taken along line 44 of FIG. 2 through an arm of the tool;

FIG. 5 is a side elevational view of the tool shown with arms in retracted position; and

FIG. 6 is an enlarged perspective view of an arm per se shown in inverted position.

Referring, now to the drawings wherein like reference characters designate like or corresponding parts throughout, there is illustrated in FIGS. 1 through 5 a grinding tool, generally designated by reference numeral 10 which has a hollow internally threaded cylindrical hub 12 formed with an integral end wall 14 (FIG. 3). This wall has a plurality of circumferentially spaced slots 16 in which are rotatably fitted a plurality of arms 18, each formed from a single strip or bar of metal as best shown in FIG. 6. At one end portion 20 the sides of the strip are pressed together in abutment and a hole 22 is formed therethrough. A V-shaped notch is formed in the free end of the arm portion 20 to define a flat inwardly extending land 24. The other end portion 26 of the arm 18 is expanded to a channel shape and has a hole 27 with slanted V-shaped end edges 28 formed in a flat back 29 of the arm 18. A pair of aligned holes 30 are formed in opposing side flanges 32 disposed perpendicular to the back 29.

The end portion 20 of each arm 18 is engaged in one of the slots 16 in hub 12 with a cross pin 33 extending through the hole 22 and is swaged or otherwise secured in a circumferential groove 34 formed in the hub 12 near the end wall 14 such that each of the arms 18 is pivotally carried by the hub 12. Inside the hub 12 is an axial bore 35 in which is an axially movable plug 36 having a head 38 which bears on the land 24 of the end notch of each arm; (see FIG. 2). A coil spring 40 is seated at one end in the plug 36 and extends axially outward; with the other end engaged by the inner end of an externally threaded adjustment nut 42 which is adjustably screwed into the hub 12 and engaged by an internal threading 44 at one end of the hub. By screwing the nut 42 inwardly of the hub 12, the plug 36 is axially advanced to cause the arms 18 to pivot further outward radially. The maximum radial expansion of the arms is thus determined by the axial position of the nut 42 and the plug 36 with respect to the hub 12. v

A shaft 48 is screwed into the nut 42 and terminates short of an internally threaded bore 49 in the nut 42. A lock nut 47 is engaged on the shaft 48 to hole the shaft in fixed position with respect to the nut 42 and vice versa. The shaft 48 terminates in a recess 50 into which is I secured one end of a short flexible coupling shaft 52. The other end of the shaft 52 terminates in a fitting 54 which may be engaged in a chuck 51 of a driving motor (not shown).-

Axially slidableon the hub 12 is a cylindrical sleeve 55, which is normally biased away from the arms 18 by a light coil spring 53 inside the sleeve surrounding the hub 12. The sleeve 55 may be advanced axially toward the arms 18 and around them to hold them in compressed position (as shown in FIG. 5) so that the arms 18 may be inserted through a hole 57 in an end wall 56 of a cylinder 58 whose internal wall 60 is to be ground by the tool 10. The sleeve 55 is provided with an integral radial, annular flange 62 which serves as an abutment against the end wall 56 of the cylinder to limit axial advance of the arms 18 in the cylinder as indicated in FIG. 1. Retraction of the sleeve 55 enables radial expansion of the arms 18 to the position showin in FIGS. 1, 2, and 3.

Each arm 18 carries a shoe 70 which is a channel shaped member and carries a flat grinding stone 71 secured to a back wall 73. In each of the side walls 69 of the shoe 70 is a hole 72 which is aligned with the hole 30 in the arm portion 26. A U-shaped spring clip or catch member 74 has an axially aligned bent end or pin portions 75 of its legs 77 inserted through the aligned holes 30, 72 to support the shoe 70 pivotally on the arm 18. The loop or bight 76 of the catch member 74 extends outwardly through the hole 27 in the arm portion 26 and the legs 77 of the loop 26 bear against the slanted camming edges 28 of the hole 27. By turning the catch member around the pin portions 75, the legs 77 are urged inwardly toward each other guided by the slanted camming edges 28 of the hole 27. This causes retraction of pin portions 75 from the holes 72 to release the shoe 70.

In operation of tool 10, the sleeve 55 is first advanced axially on the hub 12 as shown in FIG. to compress the arms 18 radially inward to maximum extent. Then the arms, shoes and grinding elements may be inserted through the narrow hole 57 in the end wall 56 of the cylinder 58. When the sleeve is retracted axially up to the head of the nut 42 (as shown in FIGS. 1

and 2) the arms 18 are released and expand to contact the inner wall 60 of the cylinder 58. The maximum radial expansion of the arms 18 is limited by the position of the nut 42 in the hub 12 so that the maximum diametral grinding of the stones 71 is thereby determined. The tool is rotated by the driving chuck 51 of the drive motor. When the grinding stones 71 reach the end edge 59 of the cylinder 58 the flange 62 abuts the end wall 56 and serves as an abutment or stop member to prevent the grinding stones and shoes from passing out of the cylinder and becoming engaged on the end wall 56. When grinding is completed the sleeve 55 may be held stationary while the tool is withdrawn axially to compress the arms 18 radially. This will permit the tool to be withdrawn through the narrow hole 57 in the end wall 56 of the cylinder.

The tool described is thus adjustable for grinding cylinders of various internal diameters. The interior of the cylinder is made accessible because of the expansible and retractile mounting of the pivotable spring loaded arms 18 supporting the grinding shoes 70 and the stones 71. Any shoe is quickly removable by manipulation of the spring catch 74 to contact the catch member on the camming edges 28 for replacement with a new shoe and grinding stone. The tool is light in weight, relatively inexpensive to manufacture, strong and durable in construction and completely reliable in operation.

It should be understood that the foregoing relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

The invention claimed is:

1. A grinding tool for a hollow cylinder having an end wall formed with a central hole, and a cylindrical inner wall to be ground, comprising a cylindrical hollow hub;

a plurality of arms pivotally mounted at one end to one end of said hub;

a plurality of grinding members respectively removably mounted to the other end of each of said arms; and

spring biased adjustment means in said hub bearing on said arms to hold them in radially expanded position determined by the setting of said adjustment means.

2. A grinding tool as defined in claim 1, further comprising axially slidable means on said hub for holding said arms in radially contracted position.

3. A grinding tool as defined in claim 1, further comprising an axially slidable sleeve on said hub for holding said arms in radially contracted position, and an annular radial flange on said sleeve serving as an abutment against said end wall of said cylinder to limit axial movement of said tool through said cylinder.

4. A grinding tool as defined in claim 1, wherein said adjustment means comprises an axially movable plug in said hub contacting said one end of each of said arms;

a coil spring engaged by said plug, and

a nut adjustably threaded in said hub to advance said coil spring and said nut.

5. A grinding tool as defined in claim 4, wherein said one end of each of said arms is formed with a notch having a land disposed to effect pivotal movement of said arm when said plug bears against said land as said nut is advanced in said hub.

6. A grinding tool as defined in claim 4, further cornprising a drive shaft carried by said nut, and a lock nut on said shaft to hold the same in fixed position in said nut.

7. A grinding tool as defined in claim 6, wherein each of said grinding members comprises a shoe; a grinding stone on each of said shoes and a spring catch pivotally mounting each of said shoes to said other end of each of said arms.

8. A grinding tool as defined in claim 7, wherein said other end of each of said arms is formed with a hole having camming end edges, said spring catch being U- shaped with legs bearing on said end edges for retracting ends of said legs from said shoe when said catch is turned against said end edges to disengage said shoe from said arm.

9 A grinding tool as defined in claim 1, wherein each of said grinding members comprises a shoe;

a grinding stone on said shoe; and I a U-shaped spring clip having legs with bent ends defining pins pivotally mounting each of said shoes to the other end of each of said arms, said other end of each of said arms being formed with a hole having V-shaped camming end edges, said legs of said spring catch extending through said hole and bearing on said camming end edges for retracting said pins from said shoe when said catch is turned against said camming end edges to disengage said shoe from said arm.

10. A grinding tool as defined in claim 9, wherein said adjustment means comprises an axially movable plug in said hub contacting said one end of each of said arms;

a coil spring engaged by said plug; and

a nut adjustably threaded in said hub to advance said coil spring and said nut, said one end of each of said arms being formed with a notch having a land disposed to effect pivotal movement of said arm when said plug bears against said land as said nut is 5 advanced in said hub. 

1. A grinding tool for a hollow cylinder having an end wall formed with a central hole, and a cylindrical inner wall to be ground, comprising a cylindrical hollow hub; a plurality of arms pivotally mounted at one end to one end of said hub; a plurality of grinding members respectively removably mounted to the other end of each of said arms; and spring biased adjustment means in said hub bearing on said arms to hold them in radially expanded position determined by the setting of said adjustment means.
 1. A grinding tool for a hollow cylinder having an end wall formed with a central hole, and a cylindrical inner wall to be ground, comprising a cylindrical hollow hub; a plurality of arms pivotally mounted at one end to one end of said hub; a plurality of grinding members respectively removably mounted to the other end of each of said arms; and spring biased adjustment means in said hub bearing on said arms to hold them in radially expanded position determined by the setting of said adjustment means.
 2. A grinding tool as defined in claim 1, further comprising axially slidable means on said hub for holding said arms in radially contracted position.
 3. A grinding tool as defined in claim 1, further comprising an axially slidable sleeve on said hub for holding said arms in radially contracted position, and an annular radial flange on said sleeve serving as an abutment against said end wall of said cylinder to limit axial movement of said tool through said cylinder.
 4. A grinding tool as defined in claim 1, wherein said adjustment means comprises an axially movable plug in said hub contaCting said one end of each of said arms; a coil spring engaged by said plug, and a nut adjustably threaded in said hub to advance said coil spring and said nut.
 5. A grinding tool as defined in claim 4, wherein said one end of each of said arms is formed with a notch having a land disposed to effect pivotal movement of said arm when said plug bears against said land as said nut is advanced in said hub.
 6. A grinding tool as defined in claim 4, further comprising a drive shaft carried by said nut, and a lock nut on said shaft to hold the same in fixed position in said nut.
 7. A grinding tool as defined in claim 6, wherein each of said grinding members comprises a shoe; a grinding stone on each of said shoes and a spring catch pivotally mounting each of said shoes to said other end of each of said arms.
 8. A grinding tool as defined in claim 7, wherein said other end of each of said arms is formed with a hole having camming end edges, said spring catch being U-shaped with legs bearing on said end edges for retracting ends of said legs from said shoe when said catch is turned against said end edges to disengage said shoe from said arm.
 9. A grinding tool as defined in claim 1, wherein each of said grinding members comprises a shoe; a grinding stone on said shoe; and a U-shaped spring clip having legs with bent ends defining pins pivotally mounting each of said shoes to the other end of each of said arms, said other end of each of said arms being formed with a hole having V-shaped camming end edges, said legs of said spring catch extending through said hole and bearing on said camming end edges for retracting said pins from said shoe when said catch is turned against said camming end edges to disengage said shoe from said arm. 